Existing narrowband telecommunications networks provide the primary means for carrying voice traffic between source and destination units. However, the existing narrowband telecommunications networks may not be able to handle the increasing capacity of voice as well as data and video traffic. Another problem arises in that these existing narrowband telecommunications networks include voice dominated digital local office, transit, and private network switches that will be in place for a long time due to the substantial investment in hardware and service software put into these digital switches. Network service providers will want to preserve the functionality of their existing revenue producing voice network systems and still be able to handle the increased capacity of the voice, data, and video traffic. Network service providers desire to reduce operational and maintenance cost by supporting only one backbone network that supports all services--voice, data, image, and video.
Further, the conventional backbone network upon which local access networks rely on uses a synchronous transfer mode signaling format that takes the form of DS0 level signals multiplexed within DS1 level signals, in turn multiplexed within DS3 level signals or as VT1.5 signals embedded within Synchronous Optical Network (SONET) STS-1 signals, in turn multiplexed within higher level SONET signals. However, Asynchronous Transfer Mode (ATM) formats allow DS0, DS1, DS3, and other service traffic types to be individually or collectively, in groups, multiplexed directly into concatenated payloads of high-speed, high-capacity circuits for transport and routing/switching purposes. The benefits of asynchronous transfer mode bandwidth management including fast path restoration and efficient bandwidth utilization drives a desire to use the asynchronous transfer mode format as the backbone for the transmission of voice traffic. Therefore, it is desirable to implement an asynchronous transfer mode backbone with existing narrowband telecommunications networks to handle increasing capacity in voice, data, and video traffic.
An ATM backbone network will need to deal with a number of new conditions. One of these conditions will be voice traffic that has not been treated to remove access network impairments before entering the broadband network as ATM traffic streams. In such a case there will be required a device that serves as a network resource to be used for network provided voice treatment.
From the foregoing, it may be appreciated that a need has arisen for a broadband asynchronous transfer mode backbone network that can ease the increasing capacity of existing local narrowband telecommunications networks. A need has also arisen to adapt narrowband voice services for transmission along the broadband backbone network. Further, a need has arisen for a new network element that provides an effective network interworking capability to allow conversion between existing narrowband telecommunication networks and the backbone broadband network.